Ronnie Gallagher is a retired environmental manager and an amateur archaeologist with a great interest in the Caucasus region, where he has carried out extensive research. He has written an interesting paper on the effects of the post-glacial flooding of the Caspian Sea and its former physical connection with the Black Sea as well as with the Arctic Ocean(a).
Gallagher has also drawn attention to cart ruts in Azerbaijan(b) similar to, but not as numerous as, those on Malta. He is also an admirer of the work of Reginald Fessenden who placed Atlantis in the Caucasus(c) and proposed that migrants from that region were responsible for kick-starting what we know as the Egyptian civilisation. The renowned Flinders Petrie and Margaret Murray were sympathetic to this view, as is Gallagher(d).
>Gallagher expanded on his view that migrants from the Caucasus had settled in Egypt, suggesting that they brought with them memories of their homeland and one of its best-known landmarks – Mount Barmak in modern Azerbaijan and used its outline to inspire the Great Sphinx at Giza(g)!!! In another paper, he expands on anthropomorphic images in Azerbaijan(l).<
His own conclusion regarding the location of Atlantis in the Caucasus region was that it was inundated as a consequence of the creation of a vast ‘flooded Eurasia’ that resulted from the collapse of glacial ice-dams(d)(h)(m), comparable with the Lake Missoula Floods in America.
Gallagher’s paper should be read in conjunction with a 2004 paper(e) from a team of Russian and US scientists that relates to a ‘Giant Siberian Lake’.
>Related to this is a recent study that has shown that 12 million years ago the same vast region was home to the Earth’s largest-ever lake, which the authors have called Paratethys(i). In fact, it is claimed that its history begins even further back at 34 million years ago and at its greatest extent stretched from Germany to China!(j)<
Gallagher’s studies in Azerbaijan continue, where he has identified an extensive number of strandlines in the region resulting from ancient catastrophic flooding.
>His presentation to the Second International Conference on the Aral Sea Problems in 2019 in St. Petersburg is available online in a lengthy and extensively illustrated pdf file(k).<
He has now published a number of extended abstracts of recent papers on the academia.edu website(g). He concluded one(f) with the following: “However, the thorny problem of what might have caused the Gilazi strandlines and the inferred worldwide flood can only be speculated on and will be controversial.
Perhaps open-minded discussion on the theories, such as the reality of the diverted Russian Rivers, an enlarged Ponto Caspian and the ingress of marine waters into the Eurasian continental interior might begin to reveal a different pre-history and provide support for a world-wide flood.”
(e) See Archive 2372)
(k) Strandlines on Azerbaijan’s Mud Volcanoes and coastal interior: New evidence of a catastrophic marine flood impacting the Ponto Caspian and Aral Sea regions with its implications to natural sciences and humankind (zin.ru)
Catastrophism today is the name given to a school of thought that supports the idea that the history of the Earth has been punctuated by natural events such as floods, fires and asteroid strikes that have caused widespread if not global devastation and that some of these events occurred within the memory of man and are recorded in worldwide mythologies.
Georges Cuvier (1768-1832) is sometimes referred to as ‘the father of paleontology’ and an early exponent of catastrophism.
Worryingly, it is now more generally accepted that further catastrophes will occur as a result of future cometary/asteroidal strikes. Nigel Cawthorne, has decided to cheer us up with his book, Doomsday , which lists 50 possible global catastrophes on the future horizon!
One such close encounter, around 2800 BC, was considered by the Christian catastrophist, Donald W. Patten, to have generated the Deluge of Noah(j) and was the source of the flood legends found around the world! Patten nominates Mars as the intruder(l), an idea also advocated by Elsar Orkan, who, however, proposes a date of around 8000 BC for this encounter.
Some readers may think that the subject has no direct connection with Plato’s Atlantis, however, his text refers to a number of catastrophic events that clearly brought devastation to Athens, Atlantis and beyond. The Flood of Deucalion and earlier inundations, Phaeton and other cosmic encounters, plus conflagrations and earthquakes all point to periods of great instability in the early prehistory of the Aegean region and quite probably much further afield.
Jürgen Spanuth devotes chapter 4 of his Atlantis of the North to an examination of “the natural catastrophes of the 13th century BC” that deals with Phaeton and the blizzard of floods, earthquakes and eruptions that beset the Eastern Mediterranean at the end of the 2nd millennium BC. Some of these matters have been recently expanded upon by Nur & Cline(f)(g) and endorsed by Stavros Papamarinopoulos[0750.73].
August 2013 saw studies published(h) which pointed the finger at climate change as the cause of the widespread political instability in that region during the second millennium BC.
Claude Schaeffer, a celebrated French archaeologist, declared in 1948 that on at least five occasions during the Bronze Age the Middle East had been subjected to widespread catastrophic destruction as a result of natural events rather than human activity.
Immanuel Velikovsky is arguably the best know of the 20th century catastrophists, who published two books in the 1950’s that provoked widespread controversy that continues today. There is an interesting albeit a sceptical review of catastrophism in the last century by Patrick Moore & Bob Forrest in Chapter 14 of More Things in Heaven and Earth(k).
Paul Dunbavin, author of Towers of Atlantis , has published a paper(n), highly critical of Velikovsky’s work. Dunbavin has researched the evidence for a number of pole shifts that are not dependent on what he describes as the “naïve astronomy” of Velikovsky.
In 1964, the Belgian mathematician René Gallant (1908-1985) published Bombarded Earth which dealt in great detail with the consequences of meteorite impacts with the earth. Gallant, perhaps because of his amateur status as a geologist, never received the attention he deserved.
More recently Allan & Delair produced another book that identified 9500 BC as the date of a global catastrophe following an encounter with a comet. Their conclusions are at variance with Velikovsky’s, particularly regarding dates. Professor Mike Baillie of Queens University, Belfast is a well-known dendrochronologist who has recently entered the debate with his book, Exodus to Arthur that adds evidence from his discipline to support the theory of cometary or asteroidal impacts with the Earth. Unfortunately his work is confined to the last 4,500 years and so casts no further light on the 9,500 BC date apart from offering support for the possibility of extraterrestrial impacts.
However, Richard Firestone and his co-authors have researched an impact ‘Event’ the occurred 13,000 years ago and caused devastation in North America including the creation of the hundreds of thousands of Carolina Bays and some of the outbursts of Lake Missoula. Like Baillie, they claim that a memory of this event has been preserved in the folktales of many of the North American Indians. This book is a must-read for anyone interested in the latest developments in catastrophist research.
The destruction of Atlantis has been linked to a number of possible catastrophic events including earthquakes, volcanic eruptions, floods and asteroid strikes. Plato’s account cites a flood as the immediate cause of the disappearance of Atlantis. In the 18th century Giovanni Carli was probably the first to link a cometary encounter with the Earth as the cause of Atlantis’ demise. This idea has been supported by numerous writers ever since, with Emilio Spedicato being one of its leading exponents today.
There are numerous sites on the Internet relating to catastrophism of which one(a) can be recommended as a good starting point for further study. Andy Blackard has listed(b) events connected with global upheavals around 3200 and 2000 BC. An Australian archaeologist, Peter Jupp, is the creator of the Ancient Destructions website(e) which deals with a number of historical mysteries including, Baalbek and Antarctica.
A more recent book by Robert Argod postulates that many of these historical catastrophes were caused by an irregular series of accelerated tectonic movements, although he does not offer a credible mechanism to explain the triggering of such upheavals. Is it possible that the strikes by or near misses with extraterrestrial objects, proposed by so many, generated the tectonic shifts proposed by Argod?
Professor Trevor Palmer has written a comprehensive history of catastrophes and catastrophism from the earliest times and its relevance today. His Perilous Planet Earth includes a couple of chapters in which he reviews Atlantis theories in the context of catastrophism.
Dr Michel-Alain Combes has a PhD in astronomy from the Université Pierre et Marie Curie (Paris VI). He has an extensive website(i) dealing with catastrophism, which translates quite well.
2012 was been promoted as the date of the next worldwide catastrophe based on a highly questionable interpretation of the Mayan calendar. New Age gurus were promising a change in global consciousness, whatever that means. If interested you can read more of this nonsense online(c) or consider a more balanced view(d).
A huge catastrophist bibliography (2010) is available online(m) with a 2020 update now available(o).
>(i) http://www.astrosurf.com/macombes/index.html (French)<
A Gibraltar Landbridge or Dam is generally accepted to have existed on several occasions during the earth’s history. There is a broad consensus among geologists that the last time an enclosed and desiccated Mediterranean had its barrier to the Atlantic breached was around 5.3 million years ago. One well-illustrated website(h) attributes this rupture to a meteor impact!
Today, we generally think of the Strait of Gibraltar as the only gateway between the Atlantic and the Mediterranean, while in fact there is evidence that millions of years ago the Strait was closed but that there were earlier access routes between the two bodies of water(n). The Betic Corridor in the north, which later became part of the Spanish Guadalquivir Basin and the Rifian Corridor in the south, in what is now Morocco.
However, a number of experts in different fields (noted by Van Sertima) have opted to suggest a more recent landbridge, perhaps 120,000 years ago, in order to explain some of the faunal migrations from Africa to the Iberian Peninsula.
>When the last opening of the Mediterranean was demonstrated by Kenneth Hsu to have taken place 5.5 million years ago, the idea of a landbridge at Gibraltar being destroyed within the memory of man seemed rather unlikely. However, when I saw the bathymetric maps of the Mediterranean produced by Brosolo, Mascle & Loubrie, relating to the Younger Dryas Period, it raised new questions for me.
However, Hsu’s date for the last flooding of the Mediterranean has, understandably, found little support from young-Earth creationists, such as Lambert Dolphin(o). and Barry Setterfield, who have striven to reconcile the irreconcilable with obscure ideas, such as changes in the speed of light!<
The 18th century writer Georges-Louis Buffon speculated as early as 1749 on the existence of a Gibraltar Dam. Alexander Braghine refers[156.21] to a Bishop Tollerat, a contemporary of Bory de Saint Vincent, claiming that a Gibraltar landbridgen was breached by an earthquake and led to the submergence of Atlantis. Unfortunately, I have been unable to track down Tollerat.
Even popular fiction featured the idea of a Gibraltar landbridge. In 1869, Mark Twain in chapter 7 of Innocents Abroad voiced a then current theory that there had been dry land between Gibraltar and North Africa allowing the passage northward of the so-called ‘Barbary apes’ that live on the ‘Rock’ today.
In 1921, H.G.Wells, in The Outline of History, offered a graphic, although speculative, description of the breaching of the Gibraltar Dam(g). He wrote that “This refilling of the Mediterranean, which by the rough chronology we are employing in this book may have happened somewhen between 30,000 and 10,000 B.C., must have been one of the greatest single events in the pre-history our race.”
Manuel Sánchez de Ocaña was the Spanish Lieuenant General during the 1909 war in Africa. In a rare 1935 book, Accion de España en Africa(a) (Spanish Action in Africa) he refers to the ancient isthmus that linked Spain and North Africa as well as landbridges linking Europe and America on which he believed Atlantis had been situated.
François de Sarre (1947- ) a noted French evolutionary zoologist who has proposed that a landbridge had existed at Gibraltar, which was only destroyed in relatively recent times, possibly in the second millennium BC. In support of his view he quotes Pomponius Mela, Diodorus Siculus and Pliny. He has also published a paper, in English, supporting his opinion with a spectrum of faunal evidence(k).
Others have ventured further and proposed that a dam existed within the experience of man and that its last destruction led to the sinking of Atlantis that many claim was located in the Mediterranean. H. S. Bellamy refers to Strato quoted by Strabo, declaring that originally the strait did not exist but that the barrier was broken through in a cataclysm. Bellamy also quotes Seneca describing how Spain was separated from Africa by earthquakes. Neither of these references could have originated without human witnesses.
Alexander Braghine also added to the idea of a relatively recent landbridge when he wrote[156.139] “We possess a whole series of records of the width of these Straits, left by ancient and medieval writers of various centuries. At the beginning of the fifth century B.C. the width was only half a mile, but the writer Euton in 400 B.C., estimated it at 4 miles; Turiano Greslio, in 300 B.C., at 5 miles; and Titus Livius, at the beginning of the Christian Era, at 7 miles. Victor Vitensa, in A.D. 400, gives the width of the Straits as equal to 12 miles, and at present it is 15 miles wide.”
C. M. Hardy subscribed to the view that there had been a dam at Gibraltar that was breached around 4500 BC with such a force that it also led to the destruction of a landbridge between Tunisia and Italy. He believed that remnants of Atlantis will be found in the seas around Greece.
C. S. Rafinesque, the famous naturalist, claimed that there was a Gibraltar landbridge that was destroyed 654 years after Noah’s Flood. These claims are to be found in chapter 14 of Vol II of The American Nations published in 1836. This volume can now be downloaded for free(e). A creationist website(i) links the breaching of the landbridge with Noah’s Deluge, which the author claims not only flooded the Mediterranean but also spilled into the Black Sea, the Red Sea and also the Persian Gulf. (see below)
The standard argument against the landbridge theory is that although the Atlantic was dramatically lower during the last Ice Age it was not sufficient to expose a land bridge between Spain and Africa at Gibraltar. However, it should be noted that the underwater sill between the Atlantic and the Mediterranean would have been much higher than now. When we consider that the breaching of a landbridge at Gibraltar would have caused an incredible flow of water through the breach (hundreds of times the flow of Niagara Falls), scouring its bottom, so that by the time the levels in the Atlantic and the Mediterranean had equalised, the erosion of the sill between them would have been considerable and when viewed today would misleadingly suggest that the Mediterranean had not have been completely cut off from the Atlantic during the last Ice Age. For the future, the consequence of this is that when (not if) the next Ice Age begins the ocean levels will have to drop even lower if the Mediterranean is to be isolated from the Atlantic once again. An example of what a sudden release of large bodies of water can do is visible in the scablands of North America, created by the breaching of the glacial dam retaining Lake Missoula.
The Spanish researcher Paulino Zamarro contends, in his 2000 book, Del Estrecho de Gibraltar a la Atlantida that a Gibraltar dam was created by silting when the Atlantic was very much lower during the last Ice Age and that it lasted until 7,500 years ago when it was breached and destroyed Atlantis, which he locates in the Cyclades, with the island of Melos containing its capital city. Details of his theory can be found on the Internet(d). A larger version of Zamarro’s map is shown below.
Other researchers such as Constantin Benetatos maintain that this idea is supported by comments of ancient writers who suggest that at one time the Mediterranean had no existence. The philosopher Strato supported by Seneca refer to the sundering of such a dam linking Europe and Africa. The same idea was expressed by Diodorus Siculus, who said that Africa and Europe were joined and separated by Heracles. Such ideas could only have arisen if there had been a Gibraltar Dam far more recently than the conventionally accepted 5.3 million years ago. The lowering of the ocean levels at the beginning of the last Ice Age and the exposure of a landbridge or dam between Spain and Morocco would have had the effect of drying out the Mediterranean due to the fact that loss of water through evaporation in the region is greater than the amount of water from rivers that feed into it.
It is worth considering that although the catastrophic breaching of the Bosporus and consequent expansion of the Black Sea is generally accepted as fact, there are no specific legends to support it apart from a reappraisal of the Flood of Noah. Therefore, it is not unreasonable to point out that a lack of local myth or legend relating to a breaching of a Gibraltar Dam is not proof that such an event did not occur. Furthermore, the area around the mouth of the Mediterranean is geologically unstable and could have been subjected to seismic activity that could have breached or even blocked the strait.
Alberto Arecchi agrees(a) with the concept of an historical land bridge at Gibraltar, but places its breach to around 2300 BC. As already intimated, Constantin Benetatos also believes(b) in the existence of the Gibraltar Dam. Joseph S. Ellul the Maltese writer was probable the first modern author to link the breaching of a Gibraltar landbridge with the destruction of Atlantis, which he claims to have been located adjacent to Malta. He identifies this submergence of Atlantis by the waters of the Atlantic with Noah’s Flood. Ellul interprets Genesis 7:11, 8:2, which refers to the “fountains of the great deep” bursting forth, as a reference to the collapse of the Gibraltar Dam. David Hatcher Childress also supports the idea of such a landbridge and has ventured a date of around 9000 BC for its collapse[620.261] and the consequent flooding of a desiccated Mediterranean.
Georgeos Diaz-Montexano, who has been searching for Atlantis off the coast of Spain and Gibraltar, has favourably referred to Zamarro’s silting theory and included the illustration, shown above, from Zamarro’s book on his websites. A further reference to silting can be read on another website(f).
When the Mediterranean eventually filled up, it is highly probable that it was then that the pressure of its waters led to the flooding of the Black Sea. It is reported that there are scouring marks at the entrance to the Black Sea that are very similar to those at Gibraltar. The date of the putative collapse of the Gibraltar Dam would therefore be marginally earlier, while the Mediterranean basins filled, than the accepted date for the breaching of the Bosporus currently calculated to have been around 5600 BC.
Robert Sarmast’s apparently dormant theory of Atlantis submerged off the coast of Cyprus under what is now a mile of water is totally dependent on the existence of a Gibraltar Dam during the last Ice Age and it being subsequently breached when the level of the Atlantic rose or the even more improbable lowering of the seafloor by a mile, as a consequence of seismic/tectonic activity in the region.
On the basis of evidence(c) offered by the quoted classical writers, the fact that sea levels rose hundreds of feet after the last Ice Age and examples of water damage to temples on elevated ground in Malta and nuraghi in Sardinia it is not unreasonable to conclude that a rupturing of a landbridge at Gibraltar within the last ten thousand year was possible if not probable.
The most dramatic suggestion regarding the creation of the Strait of Gibraltar has been offered by Terry Westerman(l), who has proposed that the rupturing of the landbridge was caused by two meteor impacts.
However, all that must be reconciled with the scientific findings of Kenneth Hsu who dated the last opening of the Gibraltar Strait to 5.5 million years ago(m).>This date has been unchallenged as far as I’m aware,<
(b) See: Archive 2365
Ice Dams were not uncommon following the ending of the last Ice Age. Glacial Lake Missoula in North West America has been estimated to have burst out every fifty years or so over a two thousand year period between 13,000 and 11,000 BC. These events are dealt with in detail by David Alt in his Glacial Lake Missoula. Lake Agassiz was another enormous lake formed by glacial run-off after the last Ice Age and at its maximum extent was larger than any lake existing in the world today. There is evidence that Lake Agassiz like Missoula also breached ice dams from time to time, discharging into the Atlantic. Other large and frequent breaching of ice dams occurred in the Siberian Altai Mountains(d)(e). A USGS report listing the largest of these events is available online(b).
Recent reports(g)(h)(i) claim that around 6200 BC the bursting of an ice dam in Canada released the melt water contents of Lake Agassiz and Lake Ojibway into the North Atlantic that resulted in Greenland being cooled by an average of 7.4ºC and Europe by about 1ºC and raising the global sea level by between one and three metres (3-10 feet).
Equally dramatic was the extent of the flooding in Eurasia following the collapse of north Asian ice dams. Ronnie Gallagher has an interesting article about this on Graham Hancock’s website(a). Gallagher favours a Eurasian location for Atlantis. Even today the retreating glaciers in the Himalayas have created lakes that threaten a number a Nepalese villages. Similar conditions exist in Peru where some years ago a flood from glacial Lake Palcacocha killed an estimated 5,000 people(j).>In 2004, another ice dam attached to the Perito Moreno glacier in Argentina also collapsed, watched by applauding tourists(k).<
Professor Neil Glasser from Aberystwyth University is the lead author of a report published in 2016 in Scientific Reports, in which the breaching of an ice dam in South America, between 11,000 and 6,000 BC, was on such a scale that it altered the circulation of the Pacific Ocean. Glasser noted(f) that: “This was a massive lake. When it drained, it released around 1150km3 of fresh water from the melting glaciers into the Atlantic and Pacific oceans – equivalent to around 600 million Olympic-sized swimming pools. This had a considerable impact on the Pacific Ocean circulation and regional climate at the time.”
(g) Science – Dec. 22, 2000
(h) Proceedingsof the National Academyof Sciences – DOI:10.1073/pnas.0510095103]
(i) Quaternary Science Reviews –vol 25, p 63]
(j) National Geographic, December 2019, p.138
The Deglaciation that occurred at the end of the last Ice Age has attracted a lot of attention from Atlantis seekers because it coincides with Plato’s apparent date for the destruction of Atlantis and provides us with a possible source of the flood that subsequently not only wiped out the Atlanteans but possibly also the Athenians. However, meltwater from deglaciation causes global sea levels to rise very, very, slowly and so is extremely unlikely to have caused the destruction of the Atlanteans or Athenians as described by Plato.
The melting of the ice caps gradually caused the ocean levels to rise over a period of thousands of years and at times the retreat of the glaciers was halted and occasionally reversed. Although the melting of the ice was relatively steady, the water produced did not always reach the sea in a steady flow. Instead, it was frequently punctuated by enormous discharges of water particularly where ice dams had retained vast melt water lakes.
In the 1920’s a maverick geologist, J Harlen Bretz (1882-1981), postulated that a huge ice-age flood had carved the landscape of Eastern Washington state, in just a few days. In spite of acrimonious opposition from the geology establishment of the day, Bretz persevered with his investigations, which eventually led to the identification of Lake Missoula as the probable culprit. Bretz was finally vindicated in 1979 when, in his nineties, he was awarded the prestigious Penrose Medal for his work(f). There is a beautifully illustrated National Geographic online article that reviews Bretz’s work(i).
These discharges of huge quantities of water are recognisable as relatively sudden spikes in the rate of sea level increases and are referred to as Melt Water Pulses WMP).
Lake Missoula in what is today the state of Montana is one of the best studied of these glacial lakes. The regular discharges from Lake Missoula, following ice dam collapses, were responsible for the creation of the dramatic Scablands of the North-Western United States. Studies have revealed that between forty and eighty such floods were released from Lake Missoula alone.
However, an alternative to Lake Missoula as the cause of the scablands has been recently proposed(g), namely, the younger-dryas comet impact event. This event was highlighted by Richard Firestone and his colleagues in The Cycle of Cosmic Catastrophes. My problem with the idea of the comet impact is that it was a single event, whereas the Missoula discharges were according to some authorities quite numerous!
The power of fast flowing water was recently highlighted by a report published(c) in the journal of America’s National Academy of Sciences, where a study of Iceland’s unpronounceable Jokulsargljufur canyon indicated that this huge feature was created in a matter of days. In Iceland, such glacial outburst floods are known as Jökulhlaups(d).
It has now been estimated by scientists that around 6200 BC the ancient glacial Lakes Agassiz and Ojibway discharged into the Atlantic Ocean. These lakes were more than twice the size of the Caspian Sea and on their own are estimated to have raised sea levels by up to 4 feet. The freshwater flow is calculated at between 25 and 50 times the flow of the Amazon River and recent studies suggest that this sudden inflow of fresh water brought the Gulf Stream to a halt for more than a hundred years. A 2016 report(e) from CAGE (Center for Arctic Gas Hydrate, Climate and Environment) suggests that the Gulf Stream was not interrupted during the Ice Age.
*Graham Hancock, in his Magicians of the Gods , reviews, at length, the theories of J Harlen Bretz and after a shared field trip and lengthy discussions with Randall Carlson, concluded that Bretz had probably only revealed part of the Scablands story. Hancock has pointed out that Bretz was unaware of the cometary impact identified by Richard Firestone et al., which coincided with the start of the Younger Dryas period 12,800 years ago. This impact theory continues to amass confirmatory data, but opposition has not abated yet. The cometary impact, the creation of the Scablands and the start of the Younger Dryas cooling period all seem to coincide temporally to a degree that strongly suggests an interconnection.*
Nick Thom has suggested that an even more dramatic consequence of the discharge from Lake Agassiz was the tilting of the Earth’s axis leading to the biblical Deluge and recorded around the world in hundreds of flood myths!
Similar melt water lakes across Northern Europe retained by ice dams produced equally dramatic discharges as the dams periodically broke. One of these occupied what is now the Baltic Sea and was 30 metres above the then ocean level before bursting into the North Sea around 10,000 BC. Less well known is the flooding that took place further east resulting in the creation of a vast inland sea of which the Black and Caspian Seas were just a small part. Ronnie Gallagher has written a revealing paper on the subject(a).
It is worth noting that, although on a smaller scale, two thirds of the thousands of Himalayan glaciers contain glacial lakes, which because of global warming today are growing at risk of bursting with consequent catastrophic results. As these glaciers retreat, apart from the damage to people and property the discharges will gradually reduce the downstream flow of water to rivers such as the Ganges.
paleoclimatologist, Hartmut Heinrich, who as recently as 1988 published evidence that there had been at least six massive discharges of icebergs from the Laurentide Ice Sheet during the last Ice Age. These discharges could have contained millions of cubic kilometres of ice and must have caused substantial sea level rises. This Laurentide Ice Sheet was an enormous mass of ice that stretched from the Arctic through eastern Canada to the northern half of the United States that covered over 5 million square miles. The weight of this ice sheet was so great that it has been calculated that it depressed the earth’s crust by nearly half a mile. A recent paper contends that it was the collapse of this ice sheet, 8000 years ago causing a sea level rise that led to the breaching of a ridge damming the Bosporus and the inundation of the then freshwater Black Sea, which flooded over 73,000 square km of land.
In the southern hemisphere it was discovered a few years ago (Science, Dec.22, 2000) that the River Amazon had experienced a doubling of its outflow between 9800 BC and 9700 BC, probably as a consequence of the melting of Andean glaciers and perhaps increased rainfall during this period. The dates proposed are very close to the 9600 BC date provided by Plato for the submergence of Atlantis.
All these worldwide discharges must have resulted in the inundation of low-lying landmasses, such as the Celtic Shelf or Sundaland, in fits and starts forcing the inhabitants of these regions to regularly migrate to higher ground.
Since it is reasonable to assume that a large percentage of human settlements were then, as now, located along coasts, particularly at river mouths, the consequence for these embryonic cultures must have been catastrophic. It is very easy to see how legends of sunken civilisations probably have a very sound basis in fact. Two books by Graham Hancock and Stephen Oppenheimer have covered this idea in greater detail, lending credibility to the idea of a sunken island such as Atlantis.
However, it can be reasonably argued that the effects of deglaciation are not what Plato described. He spoke of earthquake and a flood that overwhelmed both the Athenians and the Atlanteans. This would more closely match the aftermath of a large seismic or tectonic event that generated enormous tsunamis rather than the gradual rising of sea levels, which even at its most dramatic could never have produced the effect of sinking Atlantis overnight.
However, the waters of tsunamis eventually flow back to the sea, but Plato’s account describes the event resulting in the creation of muddy shallows. To me it sounds more like liquefaction which occurs in soil with particular characteristics when subjected to an earthquake(b), similar to the destruction of the cities of Canopus and Herakleion near Alexandria.
A website that graphically illustrates the process of deglaciation after the last Ice Age is available(h).